Copyright 2009
Installation and Operation Manual
ERU50-001
Emergency Relay Unit
SM83-ERU50-804-0
ISSUE 1.01
IMPORTANT NOTICE
Chelton Avionics Inc. doing business as Wulfsberg Electronics
Division is responsible for full distribution and revisions of
ICA's (Instructions for Continued Airworthiness).
For inquiries regarding the content and currency of this
manual contact Wulfsberg Electronics Division, 6400
Wilkinson Drive, Prescott, Arizona, 86301. Telephone (928)
756-1615 or refer to the following website:
www.wulfsberg.com for more information.
SEALED
2012.11
.19
17:46:3
2 -08'00'
ERU50-001 Emergency Relay Unit
SM83 Installation and Operation Manual
Installation and Operation Manual Issue 1.01 Page ii
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Prepared By: Checked By: Approved By:
The status of this installation and operation manual is controlled by issue shown on the title page. The
status of each section is controlled by revision shown in the footer of each page. All revisions affecting
sections of this manual have been incorporated into the latest issue.
ISSUE/REVISION RECORD
Manual Issue
Number
Section
Revision Number
Revision Description Issue Date
1.01 All DCA W12809 Nov 15, 2012
1.00 Section 1 Rev: 1.00
Section 2 Rev: 1.00
Section 3 Rev: 1.00
Initial release Oct 22, 2009
Geoff Melton
2012.11.14
18:30:02 -08'00'
Barb Page
2012.11.1
6
09:25:46
-08'00'
Zack
Pahlman
2012.11.
19
15:12:12
-08'00'
ERU50-001 Emergency Relay Unit
SM83 Installation and Operation Manual
Installation and Operation Manual Issue 1.01 Page iii
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Table of Contents
Section Title Page
1. Description
1.1 Introduction 1-1
1.2 Product Description 1-1
1.3 Design Features 1-1
1.4 Specifications 1-1
1.4.1 Electrical Specifications 1-1
1.4.2 Physical Specifications 1-3
1.4.3 Environmental Specifications 1-3
2. Installation
2.1 Introduction 2-1
2.2 Unpacking and Inspection 2-1
2.2.1 Warranty 2-1
2.3 Airworthiness Limitations 2-1
2.4 Installation Procedures 2-1
2.4.1 Warnings 2-2
2.4.2 Cautions 2-2
2.4.3 Cabling and Wiring 2-2
2.4.4 Post-Installation Checks 2-2
2.4.5 Functional Requirements 2-3
2.4.6 Minimum Performance Requirements 2-4
2.4.7 Alert Configuration 2-5
2.5 Accessories Required But Not Supplied 2-5
2.6 Installation Drawings 2-5
3. Operation
3.1 Introduction 3-1
3.2 General Information 3-1
ERU50-001 Emergency Relay Unit
SM83 Installation and Operation Manual
Installation and Operation Manual Issue 1.01 Page 1-1
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Section 1 Description
1.1 Introduction
Information in this section consists of product description, design features and specifications for the
ERU50-001 Emergency Relay Unit. All derivative product information shall be contained in the applicable
manual supplement, which may be obtained from Cobham as required.
Review all notes, warnings and cautions.
1.2 Product Description
The ERU50 is an Emergency Relay Unit for use with the Cobham Digital Audio Communication System
(DACS).
1.3 Design Features
The DACS is a management system that distributes and controls all of the transceiver, receiver and
warning source audio in an aircraft. It enables the transmission of microphone audio to a selected
Transceiver and distributes all Inter-Communication System (ICS) audio.
The ERU50 allows continued communications between a crew member and cabin crew member when
the DACS is either in Backup or Emergency mode of operation. The ERU50 is a bulkhead mounted unit.
The ERU50 is powered from the corresponding cabin Audio Control Panel (ACP) power output which
comes from the AMU50 Audio Management Unit (AMU). The ERU50 is controlled either by the
corresponding cabin ACP NORM Mode output or by the corresponding AMU ACP power output.
The ERU STATUS DISCRETE functionality is intended for activating an alert on the AMU.
1.4 Specifications
1.4.1 Electrical Specifications
Power Supply
Input Current: 500 mA maximum @ 28.0 Vdc
Normal Operating Conditions:
Nominal: +28.0 Vdc
Maximum: +30.3 Vdc
Minimum: +22.0 Vdc
Emergency: +18.0 Vdc
Abnormal Operating Conditions:
Maximum: +32.2 Vdc
Minimum: +20.5 Vdc
ERU50-001 Emergency Relay Unit
SM83 Installation and Operation Manual
Installation and Operation Manual Issue 1.01 Page 1-2
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Input Signals
Microphone Inputs
Quantity: 2
Circuit Type: Differential, passive feed through
Rated Level: 30 Vrms maximum
Maximum Current: 1A maximum
Headphones Inputs
Quantity: 2
Circuit Type: Differential, passive feed through
Rated Level: 30 Vrms maximum
Maximum Current: 1A maximum
Transmit Key Inputs
Quantity: 2
Maximum Current: 1A maximum
Intercommunication System Key Inputs
Quantity: 2
Maximum Current: 1A maximum
ERU Status Discrete Selection
Quantity: 1
Maximum Current: 1A maximum
AMU ACP 3 Power
Quantity: 1
Rated Input Level: 30 Vdc maximum
Maximum Current: 1A maximum
ACP 3 NORM Mode
Quantity: 1
Rated Level: Active low, <15 mA
Input Protection: Diode protected to +28 Vdc maximum
Output Signals
Microphone Outputs
Quantity: 2
Circuit Type: Differential, passive feed through
Rated Level: 30 Vrms maximum
Maximum Current: 1A maximum
Headphones Outputs
Quantity: 2
Circuit Type: Differential, passive feed through
Rated Level: 30 Vrms maximum
Maximum Current: 1A maximum
Transmit Key Outputs
Quantity: 2
Maximum Current: 1A maximum
ERU50-001 Emergency Relay Unit
SM83 Installation and Operation Manual
Installation and Operation Manual Issue 1.01 Page 1-3
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Intercommunication System Key Outputs
Quantity: 2
Maximum Current: 1A maximum
ACP Power Output
Quantity: 1
Rated Level: 30 Vdc maximum
Maximum Current: 1A maximum
ERU Status
Quantity: 1
Maximum Current: 1A maximum
1.4.2 Physical Specifications
Height 1.30 in (33.0 mm) maximum
Depth 2.65 in (67.3 mm) maximum
Width 4.54 in (115.3 mm) maximum
Weight 0.32 lbs (0.15 kg.) maximum
Mounting Bulkhead Mount: Four 10-32 screws
Material and Finish Metal components are brushed aluminum with
conversion coating.
Connectors One 37 pin D-Sub Male Jack post locking hardware
Bonding ≤2.5 mΩ resistance when installed in accordance with
the manufacturer’s instructions
Installation Kit ERU50-IKC
1.4.3 Environmental Specifications
Temperature -40 to +70°C (ambient)
-55 to +85°C (survival)
Altitude 50,000 feet max
Humidity 95% Non-condensing
Shock Operational shock; 6 g for 11 ms
Crash safety (impulse); 20 g for 11 ms
Crash safety (sustained); 20 g for 3 s
Section 1 ends
ERU50-001 Emergency Relay Unit
SM83 Installation and Operation Manual
Installation and Operation Manual Issue 1.01 Page 2-1
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Section 2 Installation
2.1 Introduction
Information in this section consists of unpacking and inspection procedures, installation procedures,
post-installation checks and installation drawings for the ERU50-001 Emergency Relay Unit
.
Review all notes, warnings and cautions.
2.2 Unpacking and Inspection
Unpack the equipment carefully and locate the warranty card. Inspect the unit visually for damage due to
shipping and report all such claims immediately to the carrier involved. Check that all items listed below
are present before proceeding and report any shortage immediately to your supplier:
- Warranty Card
- Certificate of Conformity or Release Certification
2.2.1 Warranty
All Cobham products are warranted for 2 years from date of installation by an authorized Cobham dealer,
to be free of defects in workmanship or performance. This warranty covers all materials and labour, but is
exclusive of any transport to deliver the defective unit to and from Cobham or its designated warranty
repair center, or any labour to remove or re-install the defective unit in the aircraft. Contact Cobham for
any questions regarding this warranty, its applicability to your units and/or for return authorization.
Cobham is the final arbitrator concerning warranty administration. Units which have been physically
damaged, burned, immersed in water or otherwise abused beyond the scope of normal use will not be
considered for warranty.
2.3 Airworthiness Limitations
The Airworthiness Limitations section is FAA approved and specifies inspections and other maintenance
required under 14 CFR §§ 43.16 and 91.403, unless an alternative program has been FAA approved.
Maintenance of the ERU50 is “on condition” only. Periodic maintenance of this product is not required.
2.4 Installation Procedures
Installation Notice
This product must be installed in accordance with the installation instructions provided in the latest issue
of this Installation and Operation Manual. All risk associated with installation of this product contrary to
these instructions shall be the responsibility of the installing agency.
ERU50-001 Emergency Relay Unit
SM83 Installation and Operation Manual
Installation and Operation Manual Issue 1.01 Page 2-2
CONFIDENTIAL AND PROPRIETARY TO COBHAM
2.4.1 Warnings
N/A
2.4.2 Cautions
N/A
2.4.3 Cabling and Wiring
All wire shall be selected in accordance with the original aircraft manufacturer's Maintenance Instructions
or AC43.13-1B Change 1, Paragraphs 11-76 through 11-78. Unshielded wire types shall qualify to
MIL-W-22759 as specified in AC43.13-1B Change 1, Paragraphs 11-85, 11-86, and listed in Table 11-11.
For shielded wire applications, use Tefzel MIL-C-27500 shielded wire with solder sleeves (for shield
terminations) to make the most compact and easily terminated interconnect. Follow the connector map in
Section 2.6 as required.
Allow 3" from the end of the shielded wiring to the shield termination to allow the connector hood to be
easily installed. Reference the interconnect drawing in Section 2.6 for shield termination details. Note that
the hood is a "clamshell" hood, and is installed after the wiring is complete.
Maintain wire segregation and route wiring in accordance with the original aircraft manufacturers
Maintenance Instructions.
Unless otherwise noted, all wiring shall be a minimum of 22 AWG. Refer to the Interconnect drawing for
additional specifications. Check that the ground connection is clean and well secured, and that it shares
no path with any electrically noisy aircraft accessories such as blowers, turn and bank instruments or
similar loads.
2.4.4 Post-Installation Checks
2.4.4.1 Voltage/Resistance Checks
Do not attach the ERU50 until the following conditions are met.
Check the following:
a) Check P1001, pins <20> <21> and <34> for continuity to ground (less than 0.5Ω).
2.4.4.2 Power On Checks
Power up the aircraft’s systems and confirm normal operation of all functions with the ERU50-001
Emergency Relay Unit connected.
Upon satisfactory completion of all performance checks, make all required log book entries, electrical
load, weight and balance amendments and other documentation as required by your local regulatory
agency before releasing the aircraft for service.
ERU50-001 Emergency Relay Unit
SM83 Installation and Operation Manual
Installation and Operation Manual Issue 1.01 Page 2-3
CONFIDENTIAL AND PROPRIETARY TO COBHAM
2.4.5 Functional Requirements
The functionality of the ERU50-001 is described in Table 1 below:
ACP1
ACP2
ACP3
ACP4
Functionality:
N N N N
USER 1 through USER 4 connected to their associated port on the
AMU
ERU Status is HI/OPEN
B/E X X X
USER 3 Mic, Phone, ICS Key and TX Key signals connected to USER 1
ACP3 is not powered
USER 4 Mic, Phone, ICS Key and TX Key signals connected to USER 2
ACP4 is not powered
ERU Status is LO/GROUND
X B/E X X
USER 3 Mic, Phone, ICS Key and TX Key signals connected to USER 1
ACP3 is not powered
USER 4 Mic, Phone, ICS Key and TX Key signals connected to USER 2
ACP4 is not powered
ERU Status is LO/GROUND
N N B/E N
USER 3 Mic, Phone, ICS Key and TX Key signals connected to USER 1
ACP3 is not powered
USER 2 and USER 4 connected to their associated port on the AMU
ERU Status is LO/GROUND
N N N B/E
USER 4 Mic, Phone, ICS Key and TX Key signals connected to USER 2
ACP4 is not powered
USER 1 and USER 3 connected to their associated port on the AMU
ERU Status is LO/GROUND
N N B/E B/E
USER 3 Mic, Phone, ICS Key and TX Key signals connected to USER 1
ACP3 is not powered
USER 4 Mic, Phone, ICS Key and TX Key signals connected to USER 2
ACP4 is not powered
ERU Status is LO/GROUND
Table 1 - ERU50-001 Functionality
Table Legend: N = Normal Mode
B/E = Backup or Emergency Mode
X = Mode irrelevant
ERU50-001 Emergency Relay Unit
SM83 Installation and Operation Manual
Installation and Operation Manual Issue 1.01 Page 2-4
CONFIDENTIAL AND PROPRIETARY TO COBHAM
2.4.6 Minimum Performance Requirements
Refer to Section 2.4.5 Functional Requirements. Electrical continuity in both default and switched modes
is shown in the tables below:
AMU50 Connections
AMU USER 1 MIC
AMU USER 1 PHN
AMU USER 1 ICS KEY
AMU USER 1 TX KEY
AMU ACP3 POWER
AMU USER 3 MIC
AMU USER 3 PHN
AMU USER 3 ICS KEY
AMU USER 3 TX KEY
ERU STATUS IN
(To Alert)
ACP1
H/S1 MIC
X
H/S1 PHN
X
ACP1 ICS
X
ACP1 TX
X
ACP3
ACP3 POWER
X
H/S3 MIC
X
H/S3 PHN
X
ACP3 ICS
X
ACP3 TX
X
ERU STATUS OUT
(To Ground)
Table 2 - Default Mode
AMU50 Connections
AMU USER 1 MIC
AMU USER 1 PHN
AMU USER 1 ICS KEY
AMU USER 1 TX KEY
AMU ACP3 POWER
AMU USER 3 MIC
AMU USER 3 PHN
AMU USER 3 ICS KEY
AMU USER 3 TX KEY
ERU STATUS IN
(To Alert)
ACP1
H/S1 MIC
X
H/S1 PHN
X
ACP1 ICS
X
ACP1 TX
X
ACP3
ACP3 POWER
H/S3 MIC
X
H/S3 PHN
X
ACP3 ICS
X
ACP3 TX
X
ERU STATUS OUT
(To Ground)
X
Table 3 - Switched Mode
ERU50-001 Emergency Relay Unit
SM83 Installation and Operation Manual
Installation and Operation Manual Issue 1.01 Page 2-5
CONFIDENTIAL AND PROPRIETARY TO COBHAM
2.4.7 Alert Configuration
When used as part of a Cobham Digital Audio Communications System (DACS), the ERU50 J1001 pin
25 (ERU STATUS OUT) is connected to AMU50 J103 pin 47 (ALERT 1). See Interconnect
ERU50\001\403-0 Note 6.
This alert must be configured through the Device Configuration Software (DevCs) to be Activation Low,
as shown below. For full information refer to the DevCs Installation and Operation manual.
DevCs Device Configuration Programmer window showing Alert 1.
2.5 Accessories Required But Not Supplied
Installation kit p/n ERU50-IKC (crimp) is required to complete the installation. The kit consists of the
following:
Quantity Description NAT Part No.
1 D-Sub, MIL Spec., 37 Socket, Crimp Housing 20-21-370
37 MS Crimp Socket 20-26-901
1 Hoods, D-Sub, Metal 20-28-037
1 Tag Ring, Shield Termination 20-30-416
2.6 Installation Drawings
DOCUMENT
REV.
DESCRIPTION
TYPE
SERIAL NO.
ERU50\001\403-0 1.00 Emergency Relay Unit Interconnect (2 sheets) All
ERU50\001\405-0 1.00 Emergency Relay Unit Connector Map All
ERU50\001\922-0 1.01 Emergency Relay Unit Mechanical Installation All
Section 2 ends following the above documents
Alert 1 configured to Active Low
ERU50-001 Emergency Relay Unit
SM83 Installation and Operation Manual
Installation and Operation Manual Issue 1.01 Page 3-1
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Section 3 Operation
3.1 Introduction
Information in this section consists of functional and operational procedures for the ERU50-001
Emergency Relay Unit.
3.2 General Information
The ERU50 is an Emergency Relay Unit for use with the Cobham Digital Audio Communication System
(DACS).
The ERU50-001 Emergency Relay Unit has no operator accessible controls. During installation, it may be
determined that internal level adjustments are required. Qualified personnel only shall complete internal
level adjustments.
Section 3 ends
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